1. Field of the Invention
The present invention relates to an improvement of a pump driving device in an engine, driving a pump shaft of a pump mounted to an engine body by a valve-operating cam shaft supported by the engine body.
2. Description of the Related Art
Such a pump driving device in an engine is already known as disclosed in Japanese Utility Model Publication No. 56-27367.
In this conventional pump driving device, a drive pin is mounted across a journal portion of a cam shaft which is supported in a bearing hole of an engine body; a notch groove is formed in a pump shaft so as to be engaged with the drive pin; and the rotation of the cam shaft is transmitted to the pump shaft via the drive pin and the notch groove. However, a mounting hole of the drive pin cannot be enlarged in the journal portion of the cam shaft in order to secure an effective support surface area of the journal portion as large as possible. Therefore, it is difficult to use a drive pin having a large diameter, and thus the conventional pump driving device is not suitable for driving a large pump suffering a heavy load.